Run a LayoutStrategy against the visible children of parentId. Returns a LayoutResult keyed by NodeId. State is opaque to this helper; callers manage it (typically via a per-container state slot).
parentId
Optional
Run a LayoutStrategy against the visible children of
parentId. Returns a LayoutResult keyed by NodeId. State is opaque to this helper; callers manage it (typically via a per-container state slot).